High-pressure pump

Abstract

A high-pressure pump ( 1 ), which serves in particular as a radial or inline piston pump for fuel injection systems of air-compressing, auto-ignition internal combustion engines, comprises a cylinder head ( 2 ) and a pump assembly ( 6 ). Here, the cylinder head ( 2 ) has a cylinder bore ( 4 ) in which a pump piston ( 5 ) of the pump assembly ( 6 ) is guided. Here, the pump piston ( 5 ) delimits, in the cylinder bore ( 4 ), a pump working chamber ( 12 ). Also provided is an inlet valve ( 20 ) which is integrated into the cylinder head ( 2 ) and via which fuel can be conducted into the pump working chamber ( 12 ). Metering of the fuel conducted into the pump working chamber ( 12 ) can be achieved by actuation of the inlet valve ( 20 ). Here, full charging of the pump working chamber ( 12 ) may take place. It is however also possible for partial charging of the pump working chamber ( 12 ) to be achieved by means of suitable actuation of the inlet valve ( 20 ).

1 . A high-pressure pump ( 1 )  for fuel injection systems of air-compressing, auto-ignition internal combustion engines, with at least one cylinder head ( 2 ) and a pump assembly ( 6 ), wherein the cylinder head ( 2 ) has a cylinder bore ( 4 ) in which is guided a pump piston ( 5 ) of the pump assembly ( 6 ), wherein the pump piston ( 5 ) in the cylinder bore ( 4 ) delimits a pump working chamber ( 12 ), wherein an inlet valve ( 20 ) integrated in the cylinder head ( 2 ) is provided via which fuel can be transferred to the pump working chamber ( 12 ) and whereby, by control of the inlet valve ( 20 ), a metered feed of the fuel guided into the pump working chamber ( 12 ) is possible. 
     
     
         2 . The high-pressure pump as claimed in  claim 1 , characterized in that the inlet valve ( 20 ) is formed as a magnetically controllable inlet valve ( 20 ). 
     
     
         3 . The high-pressure pump as claimed in  claim 2 , characterized in that the inlet valve ( 20 ) is fixed to the cylinder head ( 2 ) by means of a screw plug ( 21 ) screwed into the cylinder head ( 2 ) and that the screw plug ( 21 ) is made of a ferromagnetic material. 
     
     
         4 . The high-pressure pump as claimed in  claim 1 , characterized in that a magnet coil ( 32 ) is provided, that current flowing through the magnet coil ( 32 ) allows control of the inlet valve ( 20 ), and that the magnet coil ( 32 ) can be cooled by fuel which can be transferred via the inlet valve ( 20 ) to the pump working chamber ( 12 ). 
     
     
         5 . The high-pressure pump as claimed in  claim 1 , characterized in that the inlet valve ( 20 ) comprises a valve body ( 23 ) and a valve tappet ( 25 ) co-operating with the valve body ( 23 ) to form a seal seat, wherein the valve tappet ( 25 ) lies against the cylinder head ( 2 ), wherein a magnetically activatable solenoid plunger ( 30 ) is provided and wherein the solenoid plunger ( 30 ) carries the valve tappet ( 25 ) with it on magnetic actuation to open the seal seat formed between the valve body ( 23 ) and the valve tappet ( 25 ). 
     
     
         6 . The high-pressure pump as claimed in  claim 5 , characterized in that an adjustment shim ( 29 ) is provided which serves to specify a working air gap for the solenoid plunger ( 30 ). 
     
     
         7 . The high-pressure pump as claimed in  claim 1 , characterized in that a controller ( 38 ) is provided which controls the inlet valve ( 20 ) as a function of movement of the pump piston ( 5 ) of the pump assembly ( 6 ). 
     
     
         8 . The high-pressure pump as claimed in  claim 7 , characterized in that to reduce a filling of the pump working chamber ( 12 ) of the pump assembly ( 6 ), the controller ( 38 ) at least one of:
 a) shortens the control time at its end so that the inlet valve ( 20 ) is closed before the pump piston ( 5 ) reaches a bottom dead center, or
 extends the control time at its end so that the inlet valve ( 20 ) is closed after the pump piston ( 5 ) reaches a bottom dead center, and 
   b) shortens the control time at its start so that the inlet valve ( 20 ) is opened after the pump piston ( 5 ) reaches a top dead center.   
     
     
         9 . The high-pressure pump as claimed in  claim 1 , characterized in that the inlet valve ( 20 ) has a low pressure chamber ( 16 ) which is formed in a recess ( 17 ) of the cylinder head ( 2 ) in which the inlet valve ( 20 ) is arranged and in that at least one of the low pressure chamber ( 16 ) is closed by a screw plug ( 21 ) of the inlet valve ( 20 ), and that a supply channel ( 13 ) leading to the low pressure chamber ( 16 ) is provided and that in the supply channel ( 13 ) is arranged at least one of at least one choke ( 14 ,  15 ) and at least one damping volume. 
     
     
         10 . The high-pressure pump as claimed in  claim 1 , characterized in that the inlet valve ( 20 ) has a closing spring ( 27 ) and that the closing spring ( 27 ) has a high spring pretension. 
     
     
         11 . The high-pressure pump as claimed in  claim 1 , characterized in that the high-pressure pump is one of a radial and an in-line piston pump.